The present invention relates generally to laser scanners and, more particularly, to an improved multi-faceted optical device for use in such scanners which device is rotated about a central axis for rotational movement through repetitive cycles to reflect and sweep a laser beam through a desired optical space and a method for making such an optical device.
Scanning equipment for sweeping a light beam across a surface is used for a wide variety of reading and imaging applications. One application which is becoming more and more common in merchandising is the bar code scanner which can perform functions ranging from reading pricing labels at point of sale terminals to performing inventory control data input functions. A common problem for all scanning equipment is the ability to accurately and repetitively control the scanning beam such that the reading or imaging application is reliably performed.
The scanning or sweeping accuracy is maintained by precision operation of a reciprocating galvanometer mirror or a multi-faceted optical device which defines two or more mirror surfaces, often formed on faces of a polygon which is rotated to perform the sweeping operation. Unfortunately, such scanning devices are expensive and add to the overall cost of scanners such that the deployment and resulting convenience and improved accuracy of scanner systems may be deferred. For example, in the prior art a multi-faceted optical device employed in many scanning systems is constructed by machining a piece of aluminum or other appropriate material.
Adding to the machining costs are the costs of attaching mirrors to the machined faces of the device. The mirrors are currently manually attached and adjusted to define desired angular orientations relative to axes of rotation of the devices. Further, the mirrors are secured by means of moisture cured silicone adhesive which requires a cure time of more than 72 hours delaying production and further adding to production costs.
Since lower cost scanning devices are continually being sought and improvements in this area can greatly advance the art and benefit users of scanning equipment, it is apparent that there is a need for an improved multi-faceted optical device which can be produced more quickly and inexpensively for use in laser scanners to accurately and reliably reflect and sweep a laser beam through a desired optical space.